"Hi, I tried to do cost estimate but encountered the error above. I checked the material HKMAT. It has tick mark in Display material master. Can you help me why there is such an error? And how to solve it> Regards, LRE"

If your cost estimate is exploding all the BoM levels there may be a material at a lower level that does not have its 'material origin' field ticked in its material master, where it is required. If the error message carries further information about the error (usually the error message number and sometimes further text about the cause or nature of the error) then this may help you find the source of the problem.